1. coincidence, happenstance -- (an event that might have been arranged although it was really accidental)
2. coincidence -- (the quality of occupying the same position or area in space; "he waited for the coincidence of the target and the cross hairs")
3. concurrence, coincidence, conjunction, co-occurrence -- (the temporal property of two things happening at the same time; "the interval determining the coincidence gate is adjustable")

1.

Cavendish, I much fear there is no coincidence there. - from The Mysterious Affair at Styles by Agatha Christie

2.

"Well, there is at least a curious coincidence of dates. - from The Adventures of Sherlock Holmes by Arthur Conan Doyle

3.

He didn't call it a particularly curious coincidence most coincidences were curious. - from A Tale of Two Cities by Charles Dickens

4.

But the coincidence is probably accidental. - from The Notebooks of Leonardo Da Vinci, Complete by Leonardo Da Vinci

5.

Now that's really a coincidence second time. - from Ulysses by James Joyce

6.

The coincidence struck me as too awful and inexplicable to be communicated or discussed. - from Jane Eyre by Charlotte Bronte

7.

Don't you think that is a very strange coincidence Diana is going to lend me a book to read. - from Anne Of Green Gables by Lucy Maud Montgomery

8.

Neither did he call it a curious coincidence that true patriotism was _his_ only motive too. - from A Tale of Two Cities by Charles Dickens

9.

"What a wonderful coincidence Just during the service. - from War and Peace by Leo Tolstoy

I need hardly tell you that in families of high position strange coincidences are not supposed to occur. - from The Importance of Being Earnest by Oscar Wilde

12.

"I've often noticed that once coincidences start happening they go on happening in the most extraordinary way. - from The Secret Adversary by Agatha Christie

13.

But the coincidences in the numbers which follow are in favour of the explanation. - from The Republic by Plato

14.

the plan may at first sight seem to be modelled on the lines of Mr Craik's painstaking condensation but the coincidences are either inevitable or involuntary. - from The Canterbury Tales by Geoffrey Chaucer